I'll start by saying I am, by no means, a laundry expert. I "forget" about SO many stains I end up w/ a lot of stained items.
When I do, these are things I try, sometimes they work, sometimes they don't.
Sunning does wonders...although I ususally put them in the sun to dry after I've washed them.
I'm also a big fan of oxyclean (I use the tub of reg stuff, not the baby) and Zout. If I'm really trying to get a stain out, I'll pretreat it w/ a little Zout, start the washer on hot or warm, put in a couple scoops of oxclean and swish it until it's disolved, and let the water run until it's deep enough for my clothes to soak. Then i stop the washer and let it soak overnight. In the morning I run it like normal, and it has saved so many items for me! I've found that it works best on light colored clothes/whites.
You've reminded me I've got some baby clothes w/ stains too- I think it's just part of that new-mommy, too tired to shower much less treat stains mode of early babyhood!